On a typical weekend afternoon, Beijing's Silk Street Market buzzes with the sound of tens of thousands of tourists haggling over antiques, jewelry and knock-off Gucci handbags. Rickshaw drivers normally scoop up these marketgoers, pedal them to their hotels and return with pockets full of foreign currency  a lucrative cycle drivers can repeat dozens of times a day. In recent months, though, the Silk Street Market's once reliable bustle has thinned dramatically. "I haven't seen a single tour bus pulling into the market this morning," says Lao Qian, a 49-year-old rickshaw driver taking a long lunch break. "And I've had...